Studies will be carried out along three principal lines of research: (1) The interactions of solvent components with biopolymers and their effects on structure will be further investigated. In particular, preferential interactions of salts, sucrose and organic solvents with proteins and nucleic acids in the native and denatured states will be pursued to establish the thermodynamic contributions of these materials to the stabilization of the macromolecules in different structural states. (2) The self-association studies on L-arabinose isomerase will be continued, as will studies on brain microtubule protein association in the presence of magnesium and calcium. The participation of particular groups in the sequence of the chymotrypsins on the self-association of these enzymes will be also further scrutinized. (3) Conformational studies will be continued by chemical and spectroscopic approaches. In particular, the disulfide bond contributions to the rotational bands of lima bean trypsin inhibitor will be examined as will the optical rotation properties of various DNA fractions differing in base composition and sequence.